Treatment of motor fuel



Patented June 20, 1939 UNITE-n51:res

2,163,269 TREATMENT OF MOTORFUELI Joseph A. Chenicek, Chicago, 111., assignor to Universal Oil Products Company, Chicago, Ill., a corporation of Delaware No Drawingl -Application June28, 1937,

. Serial No. 150,761

4 Claims.

This invention relates to the treatment of motor fuel suitable for use in automotive'engines of the spark ignition type. In a more specific sense the invention has reference to a process of treatment whereby the constituents of gasolines having relatively high antiknock value can be segregated from those having lower antiknock value by relatively simple operations. Developments in internal combustion engines at the present time withthe object of increasing the fuel economy have resulted in an increase in thecompressionzratios and a need for fuels which will not detonate at the higher compressions. It isnow known as the result of a large number of extensive researches on the subject that for a given boiling range the highest antiknock values are shown by aromatic hydrocarbons and that olefins, naphthenes, and parafiins follow in order of increasing tendency to detonation. This general order may be altered somewhat by ring substitutioninthecyclic groups and by isomerism in the aliphatic compounds, the isomerscorresponding to molecules of more compact structure showing higher .antidetonating properties than the normal straight chain compounds.

All gasoline motor fuels contain varying proportions of the four main groups of hydrocarbons along with minor amounts of sulfur, oxygen, and nitrogen compounds. In straight run gasolines the proportion of parafiinic compounds is higher than in cracked gasolines, and as a consequence their antiknock value is generally lower. Even the cracked gasolines, however, unless produced by intensive pyrolysis corresponding to substantially vapor phase operations at elevated temperatures and relatively low pressures, contain considerable proportions of strictly paraffinic or at least hydrocarbons which are of a more or less knocking character and the economy of producing specially high antiknock value materials is limited by the yields from a given cracking stock. Similarly the antiknock value of straight run gasolines cannot be raised indefinitely by reforming on account of the excessive losses encountered when attempts are made to raise an antiknock value above some definite point. The present process is concerned with a method of separating gasolines and particularly cracked gasolines into fractions of relatively high and relatively low antiknock value.

One specific embodiment of the present invention comprises the treatment of gasoline with cinnamaldehyde to separate said gasoline into fractions of relatively high and relatively low antiknock value. 7 V

A series of experiments, the results of which are given in the section devoted to illustrative data, has indicated that cinnamaldehyde may be profitably employed in practice to extract high 0 .antiknock value constituents from gasolines containing substantial quantitiesof such material and leave an unextracted residue or raifinate which may be more profitably reformed to produce further quantities of high antiknock value gasoline than when admixed with the high antiknock cone stituents. The degree of extraction employed in any given case will depend upon the amount of relatively high antiknock constituents in the gaso line and the antiknock value desired in the extract so that exact proportions of gasoline and solvent cannot be stated as applicable to all gasolines. Furthermore, it has been determined that for successful solvent extraction with cinnamaldehyde, temperatures below normal atmospheric are necessary. 7 V

The preferred solvent used according to the present invention for treating gasolines is a colorless liquid having a specific gravity of 1.049, a melting point of 7.5 0. (185 F.) and a boiling point of 251 C. (484 F.). The boiling point is sufliciently above the maximum end-pointspecified for ordinary motorv fuels for. assuringa ready separation of extracted boiling range material by ordinary fractional distillation. In addition, the solvent is only very slightly soluble in water so that, if desired, steam distillation may be employed Without danger of serious contamination which would necessitate dehydration before recycling the recovered solvent for further extraction.

Cinnamaldehyde is also known as phenylacrolein and has the structural formula shown below:

This compound is relatively inexpensive and is therefore utilizable commercially for the purpose of the present invention.

Selective extraction of high antiknock constituents from gasolines may be made either by batch or continuous processes, although from the standpoint of efficiency, the method of counterfiow extraction is preferable in commercial operations. The'details of either the batch or the counterfiow continuous procedure are generally well known in commercial practice and need not be enlarged upon here since they form'no special feature of the present invention.

The following example is given to show the selective action of the cinnamaldehyde in extracting relatively high antiknock material from gasolines, although the data are only illustrative and not introduced with the intention of limiting the scope of the invention in exact correspondence therewith, since the results shown were obtained in a single batch extraction and could be improved considerably by the well known expedient of counterflow operation.

The gasoline obtained by the cracking of parafiinic gas oil from the Pennsylvania field was extracted by one volume of cinnamaldehyde at the temperature of 0 C. as shown below in the appended data. The properties of the original gasoline extracted are given in the first section of the table, while the second section shows the extraction data.

PROPERTIES OF CRACKED GASOLINE Gravity, A. P. I 54.3

100 cc. distillation I. B. P., F 98 10% v 145 20 135 30 218 241 258 E. P F Qctane No 70.5

EXTRACTION DATA Octane number Property Extract Rafiinate Octane N0 74. 1 65.8 Aniline point L 23. 2 43. 4

The foregoing specification and single numerical example have indicated the character and practical value of the present invention although it is not intended that either section shall impose undue limitations thereon.

I claim as my invention:

1. A method for segregating the relatively high antiknock constituents of gasolines from those of relatively low antiknock value which comprises subjecting, said gasolines to the selective solvent action of cinnamaldehyde, separating a lower layer consisting of a solution of the relatively high antiknock constituents in cinnamaldehyde and an upper layer comprising principally the low antiknock constituents and separately recovering the relatively high and the relatively low antiknock fractions.

2. A method for segregating the relatively high antiknock constituents of cracked gasolines from those of relatively low antiknock value which comprises subjecting said gasolines to the selective solvent action of cinnamaldehyde, separating a lower layer consisting of a solution of the relatively high antiknock constituents in cinnamaldehyde and an upper layer comprising principally the low antiknock constituents and separately recovering the relatively high and the relatively low antiknock fractions.

3. A method for segregating the relatively high antiknock constituents of cracked gasolines from those of relatively low antiknock value which comprises subjecting said gasolines to the selective solvent action of cinnamaldehyde at temperatures below that of complete miscibility. 

